GB2128776A - Control system for a solid fuel combustion appliance - Google Patents
Control system for a solid fuel combustion appliance Download PDFInfo
- Publication number
- GB2128776A GB2128776A GB08228162A GB8228162A GB2128776A GB 2128776 A GB2128776 A GB 2128776A GB 08228162 A GB08228162 A GB 08228162A GB 8228162 A GB8228162 A GB 8228162A GB 2128776 A GB2128776 A GB 2128776A
- Authority
- GB
- United Kingdom
- Prior art keywords
- temperature
- fuel feed
- firebed
- fuel
- sensed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
- F23N5/10—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples
- F23N5/102—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples using electronic means
Abstract
A control system for a solid fuel combustion appliance having a combustion chamber (2) includes a first temperature sensing probe (6), a second temperature sensing probe (10) and a third temperature sensing probe (12). The temperature differential between the temperatures monitored by the first and third probes is used to initiate or discontinue fuel feed to the firebed (4) in the chamber (2) and the temperature parameter derived from the second probe, set at the datum for a desired firebed level, is employed to prevent or discontinue fuel feed upon attainment of the desired firebed level. <IMAGE>
Description
SPECIFICATION
Control system for a solid fuel combustion appliance
This invention relates to a method and a system for controlling the fuel feed to a solid fuel combustion appliance. In recent years, continuing and increasing effort has been made to confer upon solid fuel combustion appliances an enhanced degree of amenity thereby to improve their attractiveness to consumers in the domestic sector of the solid fuel market. One of the areas in which investigations have been carried out with object in view, is that of fuel feeding where it is highly desirable to achieve automaticity.
An aim of the present invention is, therefore, to provide a method and a system for controlling the fuel feed to a soild fuel combustion appliance whereby the feeding of fuel to the appliance is regulated automatically dependent upon conditions obtaining within the appliance.
Accordingly a first aspect of the invention provides a method of controlling the fuel feed to a solid fuel combustion appliance which includes a combustion chamber adapted to contain a solid fuel firebed, and a fuel feed mechanism, the method comprising the steps of sensing a first temperature within the combustion chamber at a location above the level of the firebed to derive an indication of the condition of the firebed, operating the fuel feed mechanism in accordance with the sensed first temperature thereby to initiate or discontinue fuel feed to the firebed, independently sensing a second temperature in the combustion chamber at or near the desired level of the firebed to derive an indication of the firebed level, and operating the fuel feed mechanism to discontinue or prevent fuel feed to the firebed upon attainment of the desired level as indicated by the sensed second temperature.
The operation of the fuel feed mechanism is independently controlled by the sensed first and second temperature parameters. The first temperature parameter is indicative of the combustion conditions within the firebed and will initiate fuel feed should the temperature rise above a predetermined value thus indicating high radiation from the bed and a requirement for the addition of fuel.
Alternatively, a fall in the temperature will indicate low radiation and fuel feed will not be required. The second temperature parameter is a measure of the level of the firebed and once the second temperature reaches a predetermined value indicating proximity of the firebed level, the fuel feed mechanism is prevented from allowing fuel into the combustion chamber, notwithstanding the value of the sensed first temperature.
According to a second aspect of the invention there is provided a method of controlling the fuel feed to a solid fuel combustion appliance which includes a combustion chamber adapted to contain a solid fuel firebed, and a fuel feed mechanism, the method including the steps of sensing a first temperature within the combustion chamber at a location at or near the top thereof, sensing a third temperature within the combustion chamber at a location at or nearthe base thereof, comparing the first and third sensed temperatures to determine the differential there between as an indication of the condition of the firebed, operating the fuel feed mechanism in accordance with the temperature differential to initiate or discontinue fuel feed to the firebed, independently sensing a second temperature in the combustion chamber at or near the desired level of the firebed to derive an indication of the firebed level, and operating the fuel feed mechanism to discontinue or prevent fuel feed to the firebed upon attainment of the desired level as indicated by the sensed second temperature.
The first, second and third temperatures are continuously monitored to provide a ready indication of the conditions prevailing in the firebed and to operate the fuel feed mechanism automatically in response to those conditions.
In the method according to the second aspect, the value of the sensed first temperature will vary dependent upon the radiation from the firebed.
Thus, a rise in temperature is indicative of a requirement for fuel feed. Upon fuel feed commencing, the first temperature will fall in value as the first fuel will mask the hot firebed, whereas the value of the third temperature will rise because of the increased burning intemsity. The differential between the first and third temperatures will rise and the fuel feed will be discontinued until once again the first temperature rises consequent upon fire breakthrough the fresh coal.
Notwithstanding, any indication for fresh fuel feed to the bed, if the second temperature is sensed at a value indicative of the proximity of the firebed to the desired level of the firebed, fuel feed will be prevented or discontinued. The sensing of the second temperature thus affords a control on the level of the firebed, while the differential between the first and third temperatures is used to control fuel feed.
According to a third aspect of the invention, there is provided a control system for a solid fuel combustion appliance which includes a combustion chamber adapted to contain a solid fuel firebed, and fuel feed mechanism, the control system comprising a first temperature sensing probe locatable at or near the top of the combustion chamber and adapted, in use, to sense the temperature in that location, and a second independent temperature sensing probe locatable at or near a desired level for the top of the firebed and adapted, in use, to sense the temperature in that location, the first temperature sensing probe being adapted to operate the fuel feed mechanism dependent upon the sensed temperature to initiate or discontinue fuel feed, and the second temperature sensing probe being adapted to operate the fuel feed mechanism to prevent or discontinue fuel feed dependent upon the temperature sensed thereby. According to a fourth aspect of the invention, there is provided a control system for a solid fuel combustion appliance which includes a combustion chamber adapted to contain a solid fuel firebed, and a fuel feed mechanism, the control system comprising a first temperature sensing probe locatable at or near the top of the combustion chamber and adapted, in use, to sense the temperature in that location, a second independent temperature sensing probe locatable at or near a desired level for the top of the firebed and adapted, in use, to sense the temperature in that location, a third temperature sensing probe locatable at or near the base of the combustion chamber and adapted, in use, to sense the temperature in that location, and comparator means for comparing the first and third temperatures from the first and third temperatures sensing probes to derive a temperature differential therebetween, the comparator being adapted to operate the fuel feed mechanism dependent upon the temperature differential to initiate or discontinue fuel feed, and the second temperature sensing probe being adapted to operate the fuel feed mechanism to prevent or discontinue fuel feed dependent upon the temperature sensed thereby.
Each of the first and third temperature sensing probes is set through initial calibration. Moreover, the limits set thereby will not remain correct for all firebed conditions since these are influenced by changes in flue-draught, ash content in the firebed, air supply and addition of fresh fuel. The main temperature given by the second and third temperature sensing probes gives an indication of the burning rate within the firebed, as an increase in combustion rate will give a similar increase in temperature. This indication is used and, in use, electronically sets the limit temperatures for the control system, thereby affording a continuous automatic adjustment in accordance with the prevailing conditions in the firebed.
By way of example only, a method and a system for controlling the fuel feed to a solid fuel combustion appliance according to the invention are described below with reference to the accompanying drawings in which:
Figure 1 is a diagrammatic illustration of a combustion appliance having three temperatures sensing probes;
Figure 2a is a similar illustration to that of Figure 1 showing a first condition of the firebed; Figure 26 is a similar illustration to that of Figure 1 showing a second condition of the firebed;
Figures 3a and 3b show a further condition of the firebed;
Figure 4 shows a diagrammatic illustration of the
control system and
Figure 5a-dshows a cycle of events in the
operation of the appliance.
Referring to Figure 1, there is shown a combustion
chamber 2 of a solid fuel combustion appliance (not
shown) which also includes a fuel feed mechanism
(not shown) located above the top of the chamber 2.
Afirebed 4 of solid fuel is contained within the
chamber 2 to a desired or datum level indicated at 5.
A first temperature sensing probe or thermocouple 6
is disposed near the top 8 of the chamber 2, the
probe being, in use, inset into the wall of the
chamber 2 to avoid damage. A second temperature
sensing probe or thermocouple 10 is located at or nearthe desired or datum level 5 ofthefirebed and
is also inset to afford protection and so as not to provide a ledge on which particles can rest. Athird temperature sensing probe 12 is located at or near the base 13 of the combustion chamber 2 and again is inset for the reasons aforesaid.
In operation, the solid fuel, e.g. coal, is burnt in the firebed 4 and radiation is given off from its top surface 7. The temperature sensed by probe 6 is indicative of this radiation and the temperature sensed by the third probe 12 is indicative of the burning condition at the base of the firebed. For example, the temperature sensed by the first probe 6 may be 400 C and that sensed by the third probe 12 may be 800 C, giving a differential of 400 C. The differential is calculated in a comparator 14 shown in
Figure 4 and once the calibrated temperature differential is reached, a signal from the comparator 14 is feed via a controller 15 and a main relay 16to a drive 18 for the coal fuel mechanism, thus initiation fuel feed to the firebed 4.Fresh fuel feed to the firebed 4 masks the radiation therefrom and at the same time combustion intensity at the base of the firebed increases. For example, the temperature level sensed by the first probe 6 may fall to 1000c whereas the temperature level sensed by the third probe 12 may rise to 9000C, giving a new temperature differential of 800"C. Once this, or a desired temperature differential is reached, the comprator 14 sends a further signal to the drive 18 to halt further addition of fuel. At the same time, but independently of the first and third probes 6, 12, second probe 10 senses the temperature prevailing at the datum level 5.Thus, for example in Figure 3a, a low bed level is shown and therefore the sensed temperature will also be low allowing the fuel feed, initiated by the calculated differential, to proceed. However, if as shown in Figure 3b, the surface 7 of the firebed 4 has reached the datum level 5, a signal indicative of the higher temperature at that predetermined level, is sent to the controller 15 and is transmitted to the drive 18 to halt further fuel addition. The second probe 10, therefore, operates as a bed level limiter and effectively overrides the signal derived from the comparison between the first and third temperatures, upon attainment of the desired bed level at datum 5. Figure 5 shows a cycle of events.At (a), fuel is added to the firebed in a number of small rapid stages and is controlled dependent upon the temperature differential as derived from comparator 14 from temperatures values at probes 6 and 12. Such fuel feed replenishes the firebed with fresh fuel and provides a build-up in the firebed level As the surface 7 of the firebed 4 rises, the temperature sensed bythesecond probe 10 increases until the surface 7 is coincident with the datum lever 5 at which point (b), a signal from the probe 10 overrides the fuel feed signal to prevent further fuel addition.
As the fuel burns, the firebed tends to collapse and the surface 7 falls as indicated at (c). The radiation from the firebed again rises and the level of the firebed fills below the datum 5. Thereupon the temperature differential as between probes 6 and 12 again controls the initiation of fresh fuel feed to the firebed 4.
The method and control system according to the
invention this provide a means whereby fuel feed to the firebed of a solid fuel combustion appliance can be controlled by the burning condition in the firebed in a two fold manner. Fuel feed is initiated or discontinued dependent upon the temperature differential obtained from probes at the top and bottom of the combustion chamber, and the level of the firebed cannot rise above a datum as defined by a temperature limit imposed by a monitoring probe set at the desired bed level. There are, thus, two control paths in the system operating essentially independently one of the other, whereby the level of the firebed is controlled by the second probe which can override any fuel feed instruction from the first and third probes.
It is to be understood that whilst the invention has been described with reference to a control system having three probes, the invention also embraces a system in which only two probes are provided, one at the top of the combustion chamber and one at the datum level of the firebed.
Claims (9)
1. A method of controlling the fuel feed to a solid fuel combustion appliance which includes a combustion chamber adapted to contain a solid fuel firebed, and a fuel feed mechanism, the method comprising the steps of sensing a first temperature within the combustion chamber at a location above the level of the firebed to derive an indication of the condition of the firebed, operating the fuel feed mechanism in accordance with the sensed first temperature thereby to initiate or discontinue fuel feed to the firebed, independently sensing a second temperature in the combustion chamber at or near the desired level ofthefirebed to derive an indication of the firebed level, and operating the fuel feed mechanism to discontinue or prevent fuel feed to the firebed upon attainment of the desired level as indicated by the sensed second temperature.
2. A method according to claim 1 in which the fuel feed mechanism is independently controlled by the sensed first and second temperature parameters.
3. A method of controlling the fuel feed to a solid fuel combustion appliance which includes a combustion chamber adapted to contain a solid fuel firebed, and a fuel feed mechanism, the method including the steps of sensing a first temperature within the combustion chamber at a location at or near the top thereof, sensing a third temperature within the combustion chamber at a location at or near the base thereof, comparing the first and third sensed temperatures to determine the differential therebetween as an indication of the condition of the firebed, operating the fuel feed mechanism in accordance with the temperature differential to initiate or discontinue fuel feed to the firebed, independently sensing a second temperature in the combustion chamber at or near the desired level of the firebed to derive an indication of the firebed level, and operating the fuel feed mechanism to discontinue or prevent fuel feed to the firebed upon attainment of the desired level as indicated by the sensed second temperature.
4. A method according to claim 3 in which the
first, second and third temperatures are continuous
ly sensed.
5. A method according to claim 3 or 4 in which
the sensed second temperature is used as a para
meter to override the operation of the fuel feed
mechanism initiated by the differential between the
sensed first and third temperature parameters upon
attainment of the desired firebed level.
6. A control system for a solid fuel combustion
appliance which includes a combustion chamber
adapted to contain a solid fuel firebed, and a fuel
feed mechanism, the control system comprising a
first temperature sensing probe locatable at or near
the top of the combustion chamber and adapted, in use, to sense the temperature in that location, and a
second independent temperature sensing probe
locatable at or near a desired level for the top of the
firebed and adapted, in use, to sense the tempera
ture in that location, the first temperature sensing
probe being adapted to operate the fuel feed
mechanism dependent upon the sensed tempera
ture to initiate or discontinue fuel feed, and the
second temperature sensing probe being adapted to
operate the fuel feed mechanism to prevent or
discontinue fuel feed dependent upon the tempera
ture sensed thereby.
7. A control system for a solid fuel combustion
appliance which includes a combustion chamber
adapted to contain a solid fuel firebed, and a fuel
feed mechanism, the control system comprising a
first temperature sensing probe locatable at or near
the top of the combustion chamber and adapted, in
use, to sense the temperature in that location, a
second independent temperature securing probe
locatable at or near a desired level for the top of the
firebed and adapted, in use, to sense the tempera
ture in that location, a third temperature sensing
probe locatable at or near the base of the combus
tion chamber and adapted, in use, to sense the temperature in that location, and comparator means
for comparing the first and third temperatures from
the first and third temperature sensing probes to
derive a temperature differential therebetween, the
comparator being adapted to operate the fuel feed
mechanism dependent upon the temperature dif
ferential to initiate or discontinue fuel feed, and the
second temperature sensing probe being adapted to
operate the fuel feed mechanism to prevent or
discontinue fuel feed dependent upon the tempera
ture sensed thereby.
8. A method for controlling the fuel feed to a
solid fuel combustion appliance substantially as
hereinbefore described with reference to the accom
panying drawings.
9. A control system for controlling the fuel feed
to a solid fuel combustion appliance substantially as
hereinbefore described with reference to the accom
panying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08228162A GB2128776B (en) | 1982-10-01 | 1982-10-01 | Control system for a solid fuel combustion appliance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08228162A GB2128776B (en) | 1982-10-01 | 1982-10-01 | Control system for a solid fuel combustion appliance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2128776A true GB2128776A (en) | 1984-05-02 |
| GB2128776B GB2128776B (en) | 1986-04-16 |
Family
ID=10533328
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08228162A Expired GB2128776B (en) | 1982-10-01 | 1982-10-01 | Control system for a solid fuel combustion appliance |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2128776B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1992018812A1 (en) * | 1991-04-19 | 1992-10-29 | British Gas Plc | Thermoelectric sensor |
| US6247416B1 (en) * | 1998-04-02 | 2001-06-19 | L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude | Method of operating a furnace and device for implementing the method |
| US20110030594A1 (en) * | 2006-09-21 | 2011-02-10 | John Kimberlin | Apparatus, system, and method for operating and controlling combustor for ground or particulate biomass |
-
1982
- 1982-10-01 GB GB08228162A patent/GB2128776B/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1992018812A1 (en) * | 1991-04-19 | 1992-10-29 | British Gas Plc | Thermoelectric sensor |
| AU648163B2 (en) * | 1991-04-19 | 1994-04-14 | Bg Plc | Thermoelectric sensor |
| GB2255186B (en) * | 1991-04-19 | 1995-01-04 | British Gas Plc | Thermoelectric sensor |
| US5393222A (en) * | 1991-04-19 | 1995-02-28 | British Gas Plc | Thermoelectric sensor |
| US6247416B1 (en) * | 1998-04-02 | 2001-06-19 | L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude | Method of operating a furnace and device for implementing the method |
| US20110030594A1 (en) * | 2006-09-21 | 2011-02-10 | John Kimberlin | Apparatus, system, and method for operating and controlling combustor for ground or particulate biomass |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2128776B (en) | 1986-04-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |